Ballistic Theory, Progress report...Suitable for 5yo Kids
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From: george@briar.demon.co.uk on 12 Jul 2005 08:10 Henri Wilson wrote: > On Sun, 10 Jul 2005 16:33:25 +0100, "George Dishman" <george(a)briar.demon.co.uk> > wrote: > >"Henri Wilson" <H@..> wrote in message > >news:e0arc1lpe6dpenhsc90i7hce2sa82hfplg(a)4ax.com... > >> On Wed, 6 Jul 2005 20:04:37 +0100, "George Dishman" > >> <george(a)briar.demon.co.uk> > >> wrote: > >>>"Henri Wilson" <H@..> wrote in message > >>>news:f20hc1l3tg7k9ja2h959jujt3smv4vodtn(a)4ax.com... > >>>... > >>>> The concept of 'light wavelength' is a bit obscure. > >>> > >>>Not really, it's the distance between points > >>>of equal phase measured in the directon of > >>>propagation. > >> > >> You can say that about generated radio waves > >> but not individual photons. > > > >Another interesting subject. > > > >Consider Young's slits illuminated by a laser. > >If the setup is symmetrical you get a bright > >line in the centre with fringes either side. > >Conventionally the high brightness at a > >location ten fringes to one side is due to the > >signal interfering such that the peak through > >one slit coincides with a peak ten wavelengths > >later that has travelled a longer path having > >come through the other slit. > > > >If you reduce the brightness of the laser and > >add a shutter, you can allow single photons > >into the setup. > > That is a pretty tricky operation. True but it is done. > >At the same location as above, > >you still get a peak of probability of photons > >arriving while half a fringe either side, the > >probability is zero because a peak through one > >slit interferes with a trough 9.5 or 10.5 > >wavelengths later. That must apply to each > >photon individually. > > How about using parallel light from a very dim star instead of a laser. A laser is monochromatic, a star isn't. The linewidth is important in this case. A laser will show interference with single photons even if the difference in the path length is many wavelengths. This abstract mentions a choerence length of 50m for one laser and is nothing special, just the first that came out of Google: http://www.ingentaconnect.com/content/tandf/tmop/1998/00000045/00000008/art00003 > If single photons reach the slits, the spacing should give an indication of > photon cross section. That's a different subject, I was responding to your comment on the applicability of wavelength to single photons. > >>>> If light changes speed in flight, does the distance between > >>>> wavecrests change or not? > >>> > >>>Unless wavelength = speed / frequency, you > >>>need your "tick fairies" at every change of > >>>refractive index. Think of light passing > >>>through a sheet of glass, there must be the > >>>same number of wavefronts passing a point > >>>within the glass as points outside in any > >>>given time. > >> > >> No doubt about that one, George. > >> > >> Now, if light speed relative to a particular observer changes due to the > >> observer's motion, what would you expect happens to the 'wavelength' in > >> his > >> frame? > > > >In Ritzian theory I would expect the wavelength > >to change according to the classical formula > >for a moving observer while if SR is right, it > >should change according to the relativistic > >formula. > > I would not expect the wavelength to change at all. You are right, I was thinking it would be reduced by the distance the observer had moved but that is not correct. There is still a difference between the two theories. George
From: Henri Wilson on 12 Jul 2005 18:52 On 12 Jul 2005 05:10:05 -0700, "george(a)briar.demon.co.uk" <george(a)briar.demon.co.uk> wrote: > > >Henri Wilson wrote: >> >If you reduce the brightness of the laser and >> >add a shutter, you can allow single photons >> >into the setup. >> >> That is a pretty tricky operation. > >True but it is done. > >> >At the same location as above, >> >you still get a peak of probability of photons >> >arriving while half a fringe either side, the >> >probability is zero because a peak through one >> >slit interferes with a trough 9.5 or 10.5 >> >wavelengths later. That must apply to each >> >photon individually. >> >> How about using parallel light from a very dim star instead of a laser. > >A laser is monochromatic, a star isn't. The >linewidth is important in this case. Single photons should be monochromatic, should they not? A filter could be used anyway. >A laser >will show interference with single photons >even if the difference in the path length >is many wavelengths. This abstract mentions >a coherence length of 50m for one laser and >is nothing special, just the first that came >out of Google: > >http://www.ingentaconnect.com/content/tandf/tmop/1998/00000045/00000008/art00003 > >> If single photons reach the slits, the spacing should give an indication of >> photon cross section. > >That's a different subject, I was responding to >your comment on the applicability of wavelength >to single photons. You know my 'sawblade model' of a photon. It has a spatial regularity that shows up as 'frequency' when it passes an observer. The wavelength is fixed. It is the nature of this 'spatial pattern' that is of interest. One explanation is that the 'wave package' itself features a standing oscillation from back to front as it travels along. >> >>>> If light changes speed in flight, does the distance between >> >>>> wavecrests change or not? >> >>> >> >>>Unless wavelength = speed / frequency, you >> >>>need your "tick fairies" at every change of >> >>>refractive index. Think of light passing >> >>>through a sheet of glass, there must be the >> >>>same number of wavefronts passing a point >> >>>within the glass as points outside in any >> >>>given time. >> >> >> >> No doubt about that one, George. >> >> >> >> Now, if light speed relative to a particular observer changes due to the >> >> observer's motion, what would you expect happens to the 'wavelength' in >> >> his >> >> frame? >> > >> >In Ritzian theory I would expect the wavelength >> >to change according to the classical formula >> >for a moving observer while if SR is right, it >> >should change according to the relativistic >> >formula. >> >> I would not expect the wavelength to change at all. > >You are right, I was thinking it would be reduced >by the distance the observer had moved but that is >not correct. There is still a difference between >the two theories. Under BaT, diffraction is explained in terms of frequency, not wavelength. > >George HW. www.users.bigpond.com/hewn/index.htm Sometimes I feel like a complete failure. The most useful thing I have ever done is prove Einstein wrong.
From: George Dishman on 13 Jul 2005 03:05 "Henri Wilson" <H@..> wrote in message news:gvh8d19d0qrhqheljtd1rgec71oehjstkc(a)4ax.com... > On 12 Jul 2005 05:10:05 -0700, "george(a)briar.demon.co.uk" > <george(a)briar.demon.co.uk> wrote: > >> >> >>Henri Wilson wrote: > >>> >If you reduce the brightness of the laser and >>> >add a shutter, you can allow single photons >>> >into the setup. >>> >>> That is a pretty tricky operation. >> >>True but it is done. >> >>> >At the same location as above, >>> >you still get a peak of probability of photons >>> >arriving while half a fringe either side, the >>> >probability is zero because a peak through one >>> >slit interferes with a trough 9.5 or 10.5 >>> >wavelengths later. That must apply to each >>> >photon individually. >>> >>> How about using parallel light from a very dim star instead of a laser. >> >>A laser is monochromatic, a star isn't. The >>linewidth is important in this case. > > Single photons should be monochromatic, should they not? Frequency is a measure of momentum so an accurately known momentum implies a single frequency, but the bandwidth of a tone burst is inversely proportional to the duration. The uncertainty of the value of the momentum therefore relates inversely to the 'length' of the photon but it is hard to say where a 'long' burst of sine wave is located. This is basically another way of looking at the uncertainty principle, dx * dp has a minimum value. > A filter could be used anyway. > >>A laser >>will show interference with single photons >>even if the difference in the path length >>is many wavelengths. This abstract mentions >>a coherence length of 50m for one laser and >>is nothing special, just the first that came >>out of Google: >> >>http://www.ingentaconnect.com/content/tandf/tmop/1998/00000045/00000008/art00003 >> >>> If single photons reach the slits, the spacing should give an indication >>> of >>> photon cross section. >> >>That's a different subject, I was responding to >>your comment on the applicability of wavelength >>to single photons. > > You know my 'sawblade model' of a photon. No, I haven't seen you post that that. > It has a spatial regularity that > shows up as 'frequency' when it passes an observer. The wavelength is > fixed. > It is the nature of this 'spatial pattern' that is of interest. > One explanation is that the 'wave package' itself features a standing > oscillation from back to front as it travels along. What is it reflecting off at the ends? >>You are right, I was thinking it would be reduced >>by the distance the observer had moved but that is >>not correct. There is still a difference between >>the two theories. > > Under BaT, diffraction is explained in terms of frequency, not wavelength. I'm not quite sure what you mean, are you talking of a diffraction grating rather than diffraction itself? George
From: Henri Wilson on 13 Jul 2005 04:18 On Wed, 13 Jul 2005 08:05:58 +0100, "George Dishman" <george(a)briar.demon.co.uk> wrote: > >"Henri Wilson" <H@..> wrote in message >news:gvh8d19d0qrhqheljtd1rgec71oehjstkc(a)4ax.com... >>> >>>> >At the same location as above, >>>> >you still get a peak of probability of photons >>>> >arriving while half a fringe either side, the >>>> >probability is zero because a peak through one >>>> >slit interferes with a trough 9.5 or 10.5 >>>> >wavelengths later. That must apply to each >>>> >photon individually. >>>> >>>> How about using parallel light from a very dim star instead of a laser. >>> >>>A laser is monochromatic, a star isn't. The >>>linewidth is important in this case. >> >> Single photons should be monochromatic, should they not? > >Frequency is a measure of momentum so an >accurately known momentum implies a single >frequency, but the bandwidth of a tone burst >is inversely proportional to the duration. >The uncertainty of the value of the momentum >therefore relates inversely to the 'length' >of the photon but it is hard to say where a >'long' burst of sine wave is located. This >is basically another way of looking at the >uncertainty principle, dx * dp has a minimum >value. What if the intensity of a well filtered beam was so low that only single photons were passing at any time? > >> A filter could be used anyway. >> >>>A laser >>>will show interference with single photons >>>even if the difference in the path length >>>is many wavelengths. This abstract mentions >>>a coherence length of 50m for one laser and >>>is nothing special, just the first that came >>>out of Google: >>> >>>http://www.ingentaconnect.com/content/tandf/tmop/1998/00000045/00000008/art00003 >>> >>>> If single photons reach the slits, the spacing should give an indication >>>> of >>>> photon cross section. >>> >>>That's a different subject, I was responding to >>>your comment on the applicability of wavelength >>>to single photons. >> >> You know my 'sawblade model' of a photon. > >No, I haven't seen you post that that. > >> It has a spatial regularity that >> shows up as 'frequency' when it passes an observer. The wavelength is >> fixed. >> It is the nature of this 'spatial pattern' that is of interest. >> One explanation is that the 'wave package' itself features a standing >> oscillation from back to front as it travels along. > >What is it reflecting off at the ends? Don't know. The 'spinning +/- charge' model is easier. A bit like Len Gaasenbeek's helical wave idea. One thing is certain. Photons are not 'point particles with no structure or properties other than 'energy'.. How could they be? What would distinguish them from anything else? > >>>You are right, I was thinking it would be reduced >>>by the distance the observer had moved but that is >>>not correct. There is still a difference between >>>the two theories. >> >> Under BaT, diffraction is explained in terms of frequency, not wavelength. > >I'm not quite sure what you mean, are you >talking of a diffraction grating rather >than diffraction itself? > >George > HW. www.users.bigpond.com/hewn/index.htm Sometimes I feel like a complete failure. The most useful thing I have ever done is prove Einstein wrong.
From: George Dishman on 13 Jul 2005 05:11
"Henri Wilson" <H@..> wrote in message news:66j9d1p6b2mv01v22npju5p292nns1dm1a(a)4ax.com... > On Wed, 13 Jul 2005 08:05:58 +0100, "George Dishman" > <george(a)briar.demon.co.uk> > wrote: > >> >>"Henri Wilson" <H@..> wrote in message >>news:gvh8d19d0qrhqheljtd1rgec71oehjstkc(a)4ax.com... > >>>> >>>>> >At the same location as above, >>>>> >you still get a peak of probability of photons >>>>> >arriving while half a fringe either side, the >>>>> >probability is zero because a peak through one >>>>> >slit interferes with a trough 9.5 or 10.5 >>>>> >wavelengths later. That must apply to each >>>>> >photon individually. >>>>> >>>>> How about using parallel light from a very dim star instead of a >>>>> laser. >>>> >>>>A laser is monochromatic, a star isn't. The >>>>linewidth is important in this case. >>> >>> Single photons should be monochromatic, should they not? >> >>Frequency is a measure of momentum so an >>accurately known momentum implies a single >>frequency, but the bandwidth of a tone burst >>is inversely proportional to the duration. >>The uncertainty of the value of the momentum >>therefore relates inversely to the 'length' >>of the photon but it is hard to say where a >>'long' burst of sine wave is located. This >>is basically another way of looking at the >>uncertainty principle, dx * dp has a minimum >>value. > > What if the intensity of a well filtered beam was so low that only single > photons were passing at any time? Everything I said in that paragraph was meant to refer to a single photon. >>> You know my 'sawblade model' of a photon. >> >>No, I haven't seen you post that that. >> >>> It has a spatial regularity that >>> shows up as 'frequency' when it passes an observer. The wavelength is >>> fixed. >>> It is the nature of this 'spatial pattern' that is of interest. >>> One explanation is that the 'wave package' itself features a standing >>> oscillation from back to front as it travels along. >> >>What is it reflecting off at the ends? > > Don't know. There's the rub - two point particles? ;-) > The 'spinning +/- charge' model is easier. > A bit like Len Gaasenbeek's helical wave idea. I don't know how that differes from cirular polarisation and to be honest I'm not that interested, QED is entirely adequate. > One thing is certain. Photons are not 'point particles with no structure > or > properties other than 'energy'.. > How could they be? > What would distinguish them from anything else? You would be better to ask someone more knowledgeable about particle physics but basically the set of properties (charge, mass, spin) is unique. In fact zero mass is probably the main factor. George |